Laundry Room Standpipe - trap required?

Hello everyone,
I am in the process of redoing the layout of my laundry room (home is about 17 years old in whitby ontario) and was looking at the the existing plumbing for the washing machine.

My question relates to the p-trap. Does the standing pipe require a p-trap?
The laundry sink is nowhere near the washing machine so it does not feed directly into that line but it comes straight down into the basements, connects to an elbow joint proceeded with a long straight run that feeds into the stack via a y-attachment.

With my investigations I don't think I saw any trap coming into the basement however i didn't look inside the walls.